Digital image processing devices, such as digital cameras, or devices with such cameras, use automatic features to increase the quality of an image on the preview screen on the digital camera, the recorded pictures, and recorded video. This includes the 3A features which refers to automatic white balancing (AWB), automatic focus (AF), and automatic exposure control (AEC). Automatic focus is the automatic adjustment of the lens position relative to an image sensor or other image capture medium to obtain a sharp, clear image.
The movement of the lens is controlled by a camera actuator or motor that converts electric current, in case of a voice coil motor (VCM) actuator, into motion. The position of the lens is linearly proportional to the electric current (in mA) applied. In order to perform calculations to place the lens at a specific position, it must be determined how much electrical current should be applied to move the lens to that position. Due to manufacturing tolerances and/or other errors that can occur during manufacturing of the camera devices and the parts of the camera that hold and move a lens within a camera, a lens may shift relative to the sensor within the camera, and due to gravity or other forces, when the camera is placed in different orientations. This may result in undesirable changes in focal length and principal point from that used for calibration thereby decreasing the quality of captured or recorded images, and in turn, the accuracy of 3D depth detection on devices that provide multiple cameras for such a purpose.